Glycosphingolipid expression on murine L1-fibrosarcoma cells: analysis of clonal in vivo and in vitro selected sublines with different lung colonisation potential

Abstract

Summary The patterns of acidic and neutral glycosphingolipids (GSLs) were examined in a syngeneic tumour system in Balb/c mice consisting of closely related cell lines with different colonisation potentials directed to the murine lungs (in vivo selected highly metastatic sublines of L1-fibrosarcoma cells and their WGA-resistant mutants with low metastatic potential). GSLs were analysed by high-performance thin-layer chromatography and structurally identified by fast atom bombardment mass spectrometry combined with compositional analyses and exo-glycosidase digestion. The results suggest that highly metastatic sublines LI -LM and L1-LM12 derived by in vivo selection from mouse fibrosarcoma cells (cell line L1) exhibit a drastic increase of polar ganglioside expression and a restriction to globo-series GSLs. Contrasting with this the low metastatic mutant cells (LI-LM13WGA) express a reduced portion of acidic GSLs and exhibit a shift to less polar ganglioside components. Total cellular and plasma membrane-integrated GSLs were demonstrated to exhibit largely identical patterns. Concomitant with a significant decrease in LacCer expression a substantial reduction of GM2 and a complete lack of GM3 expression can be assigned to the highly metastatic sublines of LI-cells. On the other hand, the more polar gangliosides GM1a and, to an even greater extent, GDla (exceeding 70% of total gangliosides) accumulate on LI-LM and their clonal sublines. The shift to acidic GSLs of higher polarity is less pronounced on the low metastatic WGA-resistant mutant cells (LI-LM13WGA) showing a preponderance of GMIa. The portion of GDla within the fractions of acidic GSLs does not correspond to the cellular activities of CMP-NeuAc/GMI (a2-3) sialyltransferase measured for high and low metastatic cell variants. Total sialic acid content of the various cell lines differs, but is not associated with the metastatic potential. Gangliosides on LI-cells exhibit a significant substitution of N-glycolyl for N-acetylneuraminic acid (13%) compared to their metastatic sublines and to mutant cells (<1%). A conversion of surface exposed GDla to GMIa on membranes of metastatic cells by in situ treatment with Vibrio cholerae sialidase is associated with a significant reduction of tumour cell colonisation directed to the murine lungs.

Differential effects of synthetic sphingosine derivatives on melanoma cell motility, growth, adhesion and invasion in vitro

“…Some tumors contain qualitatively normal glycosphingolipids, but at abnormally high levels [10]. Other tumors may express particular glycosphingolipids not found in their normal tissue counterpart, which might play a key role in oncogenesis, tumor growth, escape from host immunodefence and metastasis formation [11,12]. Although glycosphingolipids are primarily located in the outer surface of plasma membranes they were also found intracellularly.…”